Re: [PATCHES] ALTER SEQUENCE

Does it make sense to avoid sequence name collisions if applications
have to refer to sequence names directly? I mean, I can imagine a case
where a restore would return a sequence name that is different from the
one that dumped it. pg_dump may be hacked to fix that (look up the
sequence for the column) but what about applications. Seems any real
solution is going to need removal of direct sequence name references in
applications.

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Rod Taylor wrote:
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> On Mon, 2003-03-03 at 20:47, Christopher Kings-Lynne wrote:
> > Hey, with this new ALTER SEQUENCE patch, how about this for an idea:
> >
> > I submitted a patch to always generate non-colliding index and sequence
> > names. Seemed like an excellent idea. However, 7.3 dumps tables like this:
> >
> > CREATE TABLE blah
> > a SERIAL
> > );
> >
> > SELECT SETVAL('blah_a_seq', 10);
> >
> > Sort of thing...
> >
> > How about we add a new form to ALTER SEQUENCE <sequence> ...?
> >
> > ALTER SEQUENCE ON blah(a) CURRVAL 10.... (or whatever the syntax is)
>
> The spec proposes:
>
> ALTER SEQUENCE <sequence> RESTART WITH <value>;
>
>
> I suppose (since SERIAL is nonstandard anyway) we could do:
>
> ALTER SEQUENCE ON table(column) RESTART WITH <value>;
>
> The problem is that we really don't have an easy way of determining if
> there is a sequence on table(column) to start with and ONLY that table.
>
> I don't think I'd want to allow that on user sequences at all because
> they're often used in stranger ways, and the user doing the alteration
> may not know that.
>
>
> As far as getting dependencies on the sequence, the currently proposed
> method of retrieving the next value of a sequence generator is 'NEXT
> VALUE FOR <sequence>' -- but Tom isn't going to like that :)
>
>
> Might get somewhere by making a special domain thats marked as being
> serial, and using that in the column. Create the sequence and tie it to
> the domain. Now you know the sequence tied to the column (because it's
> on the domain). Just disallow 'special' serial sequences & domains to
> be used in other ways.
>
> Prevention of the domain from being altered would also help, as you can
> then prevent the default from changing.
>
> --
> Rod Taylor <rbt(at)rbt(dot)ca>
>
> PGP Key: http://www.rbt.ca/rbtpub.asc
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